Abstract: A while after the compilation of the Sanskrit grammar called "Aṣṭādhyāyī" (≈ V century BC) by the ancient Indian linguist Pāṇini, commentators of this treatise began to formulate numerous metarules guiding to the correct interpretation of grammatical rules. The object of our study are these post-Pāṇinian metarules, also known as paribhāṣās. They describe the metalanguage developed by Panini, varieties of technical use of language’s expressive means in the "Aṣṭādhyāyī", they also help resolve contradictions that arise when reading grammatical rules and settle priorities in the execution sequence of grammatical operations. The material of the study are metarules collected and commented on by the Sanskrit grammarian of the XVII century AD Nīlakaṇṭhadīkṣita in his work "Commentary on paribhāṣās" (Paribhāṣāvṛtti). The purpose of our work is to expose the content of the "Commentary on the paribhāṣās", to classify the metarules collected in this work, to indicate their purpose. The method of the work is a structural and hermeneutical study of the text. For the first time, a detailed analysis of the Nīlakaṇṭhadīkṣita's "Commentary on the paribhāṣās" and the classification of the metarules collected in this work were carried out. For the first time in Russian-language literature, the content of a large number of post-Pāṇinian metarules of Sanskrit grammar "Aṣṭādhyāyī" is exhibited, as well as biographical data about the grammarian Nīlakaṇṭhadīkṣita is revealed.